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Computer Physical Security System - Memory Component Erasure/Damage Device

IP.com Disclosure Number: IPCOM000034380D
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Wittmann, EG: AUTHOR [+2]

Abstract

The use of piezoelectric sensors is shown as a means of securing a computer system by utilizing sensor outputs to trigger memory erasure or to damage components. To protect proprietary hardware and software, a security system is shown which consists of piezoelectric sensors, random-access memory (RAM) devices, electrically erasable programmable read-only memory (EEPROM) devices, and interface circuitry. The voltage produced by piezoelectric sensors is used as a means to either trigger an erase function or damage components. The sensors utilize polyvinylidene fluoride piezoelectric plastic film. In various configurations, the approximately .001-inch-thick plastic detects changes (transients) in pressure, heat, displacement, strain, or acoustics and results in voltage output signals. Output levels are typically .25 to 3.

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Computer Physical Security System - Memory Component Erasure/Damage Device

The use of piezoelectric sensors is shown as a means of securing a computer system by utilizing sensor outputs to trigger memory erasure or to damage components. To protect proprietary hardware and software, a security system is shown which consists of piezoelectric sensors, random-access memory (RAM) devices, electrically erasable programmable read-only memory (EEPROM) devices, and interface circuitry. The voltage produced by piezoelectric sensors is used as a means to either trigger an erase function or damage components. The sensors utilize polyvinylidene fluoride piezoelectric plastic film. In various configurations, the approximately .001-inch-thick plastic detects changes (transients) in pressure, heat, displacement, strain, or acoustics and results in voltage output signals. Output levels are typically .25 to 3.0 volts, but can be as high as 30 volts in some cases. The output signal decays with time, varying according to film capacitance and circuit resistance. A stronger signal is generated when the film is stretched than when compressed. Two piezoelectric film configurations are of interest. The first consists of membrane strips about
.003 x .25 x .25 inches, metallized on each side to accommodate electrical leads. These strips are attached inside the computer cover panels or within a protective sheath encasing a sensitive card assembly. If tampering results in bending or deforming the panels or sheath, electrical signals are emitted by the stressed sensors. The second configuration is that of a piezoelectric switch. The switch consists of a flexible cantilever beam (Figs. 1 and 2) with a strain sensing membrane affixed to one or both sides of the beam. One end of the beam contains electrical contacts which are inserted and soldered into a computer board. The other end of the beam is free, but is constrained by the circuit board sheath when installed. Removal or deformation of the sheath induces strain transients in the switch, producing output from the sensors. This configuration can also be modified to sense removal of the computer unit covers. The cantile...